Primal
by UlurNaga
Summary: "What would sex be like? With the bipedal you?" Love would know no boundaries. Even if that love was with a transforming robot... Optimus/OC. Contains sex scene, slight smut. Mech/Human interface. Companion fic to Primary Mechanisms.


**WARNING, THIS FIC CONTAINS SEXUAL CONTENT OF A HUMAN/MECH NATURE AND MAY OFFEND OR PISS OFF SOME IMMATURE READERS WITH NO LIVES. IF YOU DO NOT LIKE THIS SORT OF CONTENT, THEN KINDLY HIT THE ****BACK BUTTON**** IN THE TOP LEFT CORNER OF YOUR WINDOW!**

**-Also, if you haven't read my story Primary Mechanisms, or my Oneshot Prime Suspect; then this Oneshot may not make a whole lot of sense-**

**Anyway, so one of the only reasons I have written this Oneshot is because a lot of my readers to Primary Mechanisms wanted a scene with Optimus and Tessa experimenting with the bipedal Holoform.**

**I UNDERSTAND that mech/human sexual content is NOT everyone's cup of tea. So please, I beg you; if you don't want to read it than just DON'T! Don't flame me with your bullshit about "this is gross" or "I hate reading crap like this" because NOBODY is forcing you to read it. **

**Be mature, alright? If you don't like it, don't read it. End of story.**

**It's the reason I chose to do this as a Oneshot, rather than as a chapter in the original story; because this way you guys can CHOOSE whether or not you wish to read it.**

**Anyhow my wonderful readers/reviewers, I hope this is okay for you**

**As always, I apologize for any grammar errors; I'm VERY tired…**

Tessa hadn't intended to get wrapped up in her thoughts like this, but she had; her brain was running amok with information that she was trying to process properly Her mind was on the memory of when she had first seen Optimus Prime's robotic, bipedal Holoform; of how it was so much like the _real_ one. She would never admit it allowed, but her thoughts were briefly entertaining the idea of what sex would be like with a representation of his true form rather than the human one. Tess wasn't a mechanophiliac or anything of the sort, but the being that she loved just happened to be a Peterbilt truck who could transform into a girnt robot.

She would be lying to say she wasn't… _curious_.

Optimus, who had managed to steal himself away from the N.E.S.T base to spend the evening with her, was currently reclining on her couch in his human Holoform watching a news program. Tessa was sitting beside him curled under a blanket with her head rested lazily on his shoulder as she vacantly stared at the television, lost in her rather embarrassingly devious thoughts.

"Are you alright?" he asked her suddenly, turning away from the screen to look at the outline of her face in the otherwise dark room. She shook her head dazedly before looking at him.

"Huh? Oh, sorry, Chief…I was just…thinking."

"What about?" he asked curiously as he reached up to touch her hair, a reflexive habit that he seemed to enjoy.

In response, she tried to shrug and minimize her thoughts, "Nothing really, not anything important anyway." The little mechanic was unable to hide the embarrassment that turned up in her cheeks as she smiled unwillingly while speaking. Optimus, who knew her inside and out, was easily able to see the reaction and he smirked playfully in response.

"You're lying." He chuckled, "Please…tell me what you're thinking."

The Holoform's nimble, strong fingers twined around to play with the hair at the nape of her neck, making her giggle, "_Don't_!" she tried to demand; with no real conviction in her voice, "I can't say no when you do _that_." A pleased rumbled rolled up his chest as he leaned forward and planted a sweet kiss on her jawline before pulling back to view her again.

"I know." He said gently, "Tell me."

With an almost defeated sigh, she smiled and returned his gaze; an embarrassed blush running across her cheeks, "Well…to be honest I was thinking about…the Holoform. Not this one," she reached up and touched his chin gently before continuing, "The one that looks like the _real_ you."

"The bipedal Holoform? What about it?"

He noticed her shift a little, seemingly uncomfortable under his gaze; her fingers twisted into the blanket almost nervously and this made him doubly curious. Running her fingers through her loose, auburn waves, she averted her eyes and bit her lip.

"I was thinking…about what…_it_ would be like. You know, if we tried with the bipedal…"  
>He felt the stomach of the Holoform sink a little, not quite understanding her words; but having a fair idea of what she was getting at. He needed to clarify. Now.<p>

"What do you mean?" he asked firmly.

At this point, the poor girl resembled a tomato as she cleared her throat and scratched the back of her neck awkwardly. "Well…I…I mean _sex_, Chief. I was just…um…well _curious_ about how we could try it in that form-"

"-No." he said immediately.

Her eyes widened in surprise at the blunt and sharp response, "No?"

"No." he affirmed.

She shuffled a little bit to a more comfortable point to view him and cocked her head at him a little; like a confused puppy. "Why?"

"Because I will not." He said simply, almost insistently.

"…Because it…feels false?" she asked curiously, shifting forward so that her knee touched against his; expression one of genuine interest and curiosity, laced with concern.

The human Holoform shook his head and reached out to touch her chin, "No, it isn't that. I could overlook that sense of falseness if it meant being with you in such a way…but…" she noticed his eyes close and he exhaled heavily with a sigh before he continued, "But a bipedal Holoform retains…_Cybertronian_ instincts."

This made her doubly curious. "But…don't you have those _already_?" she scratched the lobe of her ear habitually as she leaned on his shoulder; inhaling deeply enough that she could taste his scent on her tongue. Like grinder sparks and the metal she loved so much; everything about him was so perfect to her. The mechanic in love with the mechanical man…it was like something out of science fiction; and she didn't care.

Optimus, whose fingers had moved from her chin to cup her throat tenderly, gave a perturbed expression; as if pondering how best to explain his next words. "The real me, yes…but in the human Holoform my reactions are distinctly…_human_ in nature. Instincts are closer responsive to those of your own race. But in a Cybertronian Holoform, it regards interface _as_ Cybertronian; the instincts are like those of interfacing in true form."

"But that doesn't explain…why you won't…?"

Turning her face to look at him, his glowing blue eyes bore into hers, trying to portray the magnitude of his words. "Cybertronian sexual interface is _brutal_. We are made of metal, Tess; our bodies are designed to withstand such treatment. Yours…" he traced a finger over the tenderly soft skin of her lips to prove his point, "…is not."

Unable to fight the urge to kiss him, she leaned forward and planted her mouth firmly, but briefly against his before withdrawing with a concerned expression, "But…your Spark… Would it really let itself _hurt_ me like that?"  
>Another sigh answered her as he spoke, "Not intentionally, no. But Tessa you must remember, my Spark was designed to love a Cybertronian; yet it has chosen to love <em>you<em>." Almost in reassurance to her, he clutched her chin and lowered his lips over hers; kissing her insistently before he spoke again, "And I would not change that for _anything_. But it was not intended to spark interface with a human. My people are stronger than your own, and I fear what could happen to you if I were to attempt it; I would sooner throw myself into the Pit than see you harmed at my hand."

The little mechanic had quietened a fraction now, clearly thinking something over as she took his hand; her eyes focused intently on his as a faint pink dusted her cheeks. "But…what if I _wanted_ to try…?"

"No."

:But Optimus-"

"-_No_."

His voice was harsh, but his eyes were tender; and she knew that he was only being short with her because of his fears about the path she was trying to lead him down. His fingers intertwined with hers and he shook his head in reaffirmation.

"Tess…why would you _wish_ for an interface with a robotic form, when your race is not pre-programmed to be _attracted_ to a machine in the first place?"

A smile crossed her face at his words, and suddenly she felt sure; certain that she truly did want to at least _try_ this with him. Keeping their fingers intertwined, she pushed the blanket off herself and swung her leg over his hips so that she was sitting backward in his lap. She released his hand and laced her fingers at the nape of his neck; her forehead pressed against his own as she briefly planted a kiss on his lips.

"Maybe not, but I'm attracted to _you_. In whatever form you exist in, Chief; you _know_ that." Her hands slid gently from his nape, around to rest on his chest as she leaned down and kissed at his neck; her nails tickling at his pectoral muscles. The skin beneath his shirt twitched at the touch and his shoulders flexed as his fists clenched with the effort of trying to resist the urge to tangle them into her long hair. He knew what she was trying to do, that she was trying to distract him with affection; and he would be lying if he said it wouldn't work.

"Stop that." He said firmly, trying to make it sound like an order.

Knowing full-well that he had no power to stop her, she opened her mouth a little and dragged her tongue over the skin of his throat; feeling the hum of Energon beneath it. "Mmmmake me…" she whispered against his skin with a playful smile, "I _dare_ you."

"Arh…mmm…Tess…" he rumbled, unable to stop his hands from moving to her legs; gently tracing the fabric of her pyjama pants with his fingertips, "Stop. I won't give in to your _seduction _methods..."

Her nails traced teasingly along the thick musculature of his forearms just as she nipped at the join in his neck and shoulder, "…You sure about that Chief?" she whispered onto his skin.

"N..Mmmah…not really…"

"Please Optimus…_Please_ can we just…_try_?"  
>"…No..." he murmured unconvincingly, sounding almost afraid, "I could very seriously hurt you."<p>

She pressed her nose under his chin and nuzzled against his firm skin, "I _trust_ you; and I trust your Spark. You won't hurt me, you _couldn't_ hurt me."

His hand reached up from her thigh to take her wrist in his grasp gently, causing her to look up at him. There was a very serious expression showing in his eyes, an apprehensive one. "I understand fully that my Spark would never intentionally harm you, but I am talking about in terms of _physical matter_. While an interface could very well be _possible_, your body is not designed for the potential _violence_ that Cybertronian sexual encounters pose. I would lose myself to instincts that I have not relied on in a very long time, very primal instincts, Tessa."

"Well if you haven't used them for a long time…" she pressed a kiss to the hollow of his throat, "…then how do you know things might not work out. What if we _did_, and it went amazing?"

Drawing her hand from his grasp, she pinned his shoulders gently into the back of the sofa and planted a languid kiss on his lips. Her fingers tickled the material of his shirt as they traced over his shoulders and across his chest; down the canyon of his abdominal muscles to his navel. "T…Tess…please…" his protests were not strong now; she had all but won this fight. Planting her hands on his hipbones, she pressed her forehead to his and tightened her legs against his.

"Trust _me_." She begged him, "I want this…I want _you_; in whatever form I can get you… _Please_?"

His hands rested at her hips before his fingers tightened there; a heavy, resigned sigh escaping him, "I don't want to hurt you…Tessa, there will be a point of no return with this; and then I will not be able to coherently control myself. Even in _human_ form my desire for you can be…blinding. Combining that alone with Cybertronian interfacing instinct…and it could be very dangerous for a race as delicate as yours…"

Exasperated, she went to rebuke him, but he cut her off, "Chief-"

"-You must promise me something, if you _insist_ that we do this…"

"What?"

He pulled her down against his chest, holding her tightly in a hug as he rumbled into her hair, "If it gets dangerous…Tessa, if it gets out of control…you must do _anything_ you can to get away; even if it means attempting to incapacitate me…"

With a concerned smile, she planted her lips against his throat and slid her hands up under his shirt teasingly, "It won't come to that…but I promise."

"Are you sure-?"

"-Chief!"

Another resigned sigh, "Alright…" he rumbled, lifting her higher in his lap and sealing his lips at her throat in a kiss. He traced his tongue gently over her jugular, feeling her life pulsing in the veins beneath her skin. "…you win…"

He felt her fingers tighten on his hips and she couldn't restrain a whispered giggle as he nuzzled into her. Tess would be lying to say that her heart didn't jump a little in nervousness; with trepid excitement. The path they were heading down was completely uncharted territory; there had never been a relationship quite like theirs…and every venture was a mapping process of both their bodies _and_ their minds. Sliding her hands teasingly up under the Holoform's shirt, she tickled at the skin with her nails and planted a chaste kiss against his mouth.

"Come on, get rid of this one. Show me the other Holoform." She murmured.

With a defeated rumble, the human body beneath her began to illuminate with the familiar, tiny electrical pulses. She clambered off his form and stood in front of the couch as she watched it transform into neon, electrical glow.

The bluish silhouette changed shape, growing and moving. The body became sharper, broader; more angular and rigid. The shape of smokestacks rose at his shoulders and his limbs became broader, more boxed in shape. As his body started to regain colour, and the illuminative sparks died down; she was greeted with the sight of a miniature bipedal Optimus Prime reclined on her couch.

The sofa sank heavily as his body came into physical matter, the weight of the metal much heavier than human skin and bone. His head rested against the back of the couch in an almost bracing manner before he heaved his body up. The gears and joins in his metal Holoform hissed and whirred as he stood towering over her at a good 6 or 7 feet; his shadow blocking out the dying sunlight light behind them.

He noticed her swallow thickly, the rise of her throat moving a little at the action. His optics narrowed with a whir and he carefully, _ever_-so-carefully, lifted a large metal hand to touch her chin, "It isn't too late to back away from this…" he tried, sounding very much like he wanted her to take his advice.

A small smile quirked up into the corner of her lip as she closed her eyes and clasped one of her hands over the fingers that touched her face, "Optimus I _want_ to do this. Show me how..."

Sliding the metal digits down over her throat, he cupped the rounds of her shoulders in both hands before lowering his face to hers; his neon optics surveying her intensely. He gave an exhaling sigh against her; the decompression of air tickling her lips before he pressed his metal mouth against them.

A muffled sound of encouragement escaped through her nose as her hands pressed against his chest plating; against the miniature hood that plated there. In the back of her mind, she entertained the thought of what he would look like if he transformed into alt mode right now; a little mini-Peterbilt that would probably resemble a remote controlled car.

Unable to restrain herself, she giggled into his mouth; the metal cold and cumbersome against her own.

With trailing, venturing fingers, she traced the sharp angular curves of his body; mapping every crevice and raise. Sliding the digits underneath one of the plates, she dragged her nails across the sensitive under-metal; an action which drew out a groan from him against her lips. She stepped forward into him, trying to push him back onto her couch. When he realized what she was trying to accomplish, he complied; backing up a few steps to sit on the aforementioned furniture.

Tess resumed the position she had been in with the human Holoform, one leg either side of his hips as he sat. Taking the vents of his face in her hands, she planted a kiss on the vertical, metal seam at the bridge of his nose before she spoke in a murmured; pressing her forehead to his.

"_Teach_ me, Optimus…" she whispered, pressing her mouth to his insistently.

With a rumbling growl, she felt his _cold_ metal fingers rest on her thighs as the plating of his mouth moved against hers. It was slow, mapping; a delicate process of something new and different. Tessa's heart fluttered at the idea that this would be as close as she could get to actually physically _being_ with Optimus' real body.

Suddenly, she felt something warm and damp touch the corner of her mouth, tracing the bottom of her lip softly. She gasped through her nose as it tentatively slid past her lips and traced the line of her teeth, pulling herself back a little to look at him with a wide-eyes expression.  
>"<em>Optimus<em>? What was _that_?" she exclaimed in surprised, her fingers lingering on the vents of his cheeks. He watched her intently, gaging her reactions and responses.

"It was referred to as a '_glossa_' on Cybertron; it is our race's equivalent to a tongue muscle. We also do have something mildly resembling teeth. '_Dentas_' we call them. " He lifted a hand from her thigh to trace a finger under her chin and pulled her down a little so that their faces brushed closely, "We can stop, Tessa…you need only say – _Mmph_-!"

She cut him off by pressing her lips over the metal again, being so adventurous as to venture out her own tongue and taste the metal. It was so wonderfully _him_.

"Stop – mm – stop trying to – _mph_ – make me s_top_." She murmured against him, "No more of that."

"But Tess – Aargh-_Tessa_!"

Her lithe, oil-stained little fingers had dipped beneath the join between plating at his hips, teasingly stroking the sensitive protoform matter beneath. She smiled playfully to herself as she noticed him arch at the touch and separated their mouths.

Sweet _Primus_ it was like Heaven.

"Unmerciful _Pit_," he hissed under his breath, "Tessa do that _again_."

With a smile, Tessa tucked her legs tighter around him and traced her fingers teasingly over the metal exterior; the teasing touches not quite mimicking the sensation from earlier. "That feels good?" she asked, "So…it's like _humans_? Chief, you have to teach me what you like in this form…I've never done anything like this with you…"

He gave a slow thoughtful nod before lifting a hand to the hem of her shirt, "Remove this…I have an idea." With a decadent little smile, she planted a kiss on the seam of his nose and lifted her arms over her head.

"I trust you."

Understanding her compliance, he wormed the metal digits of his fingers underneath the fabric; delighting in feeling her squirm at the comparatively cold touch. The garment lifted away over her head easily, revealing her light, supple skin beneath it. As he removed it, the smallest fingers of his hands hooked the hem of her sleeping bra underneath and removed that as well. The tiny mounds of soft flesh were exposed to the air and she gasped as her nipples became tight at the shift in temperature. Out of modest habit she lifted an arm to cover herself, but Optimus' large hand grasped her wrist tenderly.

"Don't do that…" he rumbled gently, "You're beautiful."

His face moved to the gap between the rounded curves of flesh and nuzzled his nose against the skin over where her heart was beating within her ribs. A hand on her back guided her forward as his chest plates split open; revealing the crackling energy of the Holoform's Spark. It wasn't as intense as his _real_ spark, but it was a representation; and that was enough to serve the current purpose he required.

Tessa felt him pressed her against his chest; felt her _heart_ beating against his Spark. It was incredible, like feeling the engine of a motorcycle rumbling against her ribs; it was almost energizing to experience, and left her more than a little breathless. Comforted completely by the feeling of his life source against hers, she didn't notice the pleased tension in Optimus' shoulders, or the rumbling growl that originated from deep within his chest.

Her fingers traced down over his sides to his hips, tickling at the outside of his tapered metal thighs. As she gently dug her fingers into the crevices of plating again, she noticed the metal that she was seated on was warming a little…

"Chief…?" she murmured into his neck, "What's that warmth. It…_mm_…it feels nice."

To her surprise, he growled lowly before he answered, pulling her tighter against his chest. As a human, she couldn't possibly know how pleasurable such closely intimate contact was. For Cybertronians, Spark to Spark touch was something remarkably intense.

"An interface panel." Optimus explained, trying to refrain a rumble from bubbling up out of his vocals, "For retaining and protecting a mech's…_equipment_…"

"Hmm…" she murmured thoughtfully, digging her fingers deeper under the metal, stroking the sensitive matter underneath. She noticed his fingers tighten around her thighs a little bit, and this encouraged her to take a bigger step, "Well _un_retain it."

"It will be dangerous…As soon as it is released, my control is – Argh!"

In almost annoyed retaliation, she had brought her hands up to his Spark and dragged her nails from its top to the bottom; relishing in the near full-bodied convulsion he gave, a growl rumbling through his entire chest chamber. "_Do_ it." Tess growled back, tightening her legs around his form; feeling metal plating press awkwardly into her legs as she did so.

It felt a little strange, admittedly, because this body was not soft and malleable. It was hard, metal and immovable; strong and infinitely more rigid than a human one. She heard a strange click, followed by a brief whirring noise below her before Optimus' metal lips pressed to her throat; the '_glossa_' tracing wetly across the skin there. She bent her own face down to his neck and nuzzled her nose there; noticing a connection of cables and thick wires.

Feeling adventurous, Tess reached up from his Spark and gripped the smokestacks on his shoulder tightly before taking one of the cables between her teeth gently. She grazed them along the thick length of insulated wiring before biting down a little bit; not hard enough to hurt, but enough to get a reaction. However she hadn't been _expecting_ the reaction that she got.

The casing of his Spark rattled almost aggressively before his large metal hands moved to her butt, pulling her hips into his own. She noticed a warm protrusion press against the intimate fork of her legs, and that was when she realized that it was apparently his interfacing equipment. A brief frisson of fear struck through her chest, but it was extinguished by the rather trepid excitement that she felt.

Tess would probably too embarrassed to admit it out loud, but Optimus being in charge and out of control…_excited_ her in more than one way.

With an encouraging moan, she gripped the smokestacks tighter and ground her hips against the panel as she bit down a little harsher on the cable at his neck. A metallic, Cybertronian growl that greatly resembled cell phone interference resounded from him as his hand moved to her waist. He gripped her tightly and lifted her, snapping the panels of his chest shut tightly before he shoved her, actually _shoved her_, down onto the couch. His hips were planted around her knees and his strong, powerful arms boxed her into the cushions; his face inches from hers with an almost _dominating_ expression.

His glowing blue eyes appeared darker than usual; probably the Cybertronian equivalent of lust.

"Mine." He growled, bending his head to trace his glossa along her throat again, over her collarbone demandingly.

Tessa giggled at the warm, ticklishly damp sensation from the malleable piece of metal against her skin, tilting her head back a fraction to allow him the access he clearly wanted. "Mmm…Optimus…" she reached her arms up to the metal of his 'abdomen' to drag her nails up along it. However her actions were cut off as his large metal hands fumbled down to seized her wrists and pin them almost brutally above either side of her head. The metal of his lips had bared to reveal the metal plating he had spoken of that acted as teeth. His expression was dark, and easily identifiable as lust.

"_Mine_!" he snarled at her, an almost lion-like growl trembling up his vocal processors; shaking her very soul and making her legs tremble a little.

"Yours." She smirked, knowing full-well that he was probably not coherent right now; acting on instincts rather than reason. She arched her back, lifting one of her knees to teasingly press it against the 'equipment' between his thighs as she encouraged him, "_All_ yours."

Seemingly pleased at her compliance, his head lowered to her bared breasts and nuzzled them each in turn before nipping at her ribcage with his dentas. She gasped at the sensation and arched her back again; a motion that the Holoform robot took advantage of by sliding a hand underneath the small of her back and continuing to pinch the skin between his teeth.

The sharp parts and joins of his metal body felt weird against her bare skin, but it was just an unusual sensation. Ignoring it, she used her free hand to wrap around the back of his helm and dragged her nails across the metal. The sound was like nails on a blackboard, but clearly it felt _good_ for him, because the primal Holoform encouraged her actions with a grunt before grinding his hips slowly into hers; a growl rupturing up his chest.

The sun had set now, and the room was getting quite dark; Tessa wanted to be able to see so that that could move this romp to a more…_appropriate_ room in her household. Wriggling in his grip, she wormed her body toward the side table where the lamp sat, in an attempt to turn it on and get some lighting. However Optimus gave a vicious snarl and dug his fingers into her thighs, yanking her back down beneath him as his 'teeth' bared in almost animalistic fury.

"Don't _move_!" he rasped deeply.

Wrapping her hips around him, she aggressively bared her teeth him in return; decided that if Cybertronian lovemaking was brutal, she wasn't going to take it lying down. She reached up and seized his finial gears in her fingers tightly as she growled back at him, "_Mine_."

Optimus froze briefly for a second, clearly taken aback by his femme's reciprocated possessiveness. His optics whirred as they shuttered, watching his female with lustful interest; then his hands reached under and curled around her legs, pulling her pelvis flush against his hips and holding her there as he growled.

It was…_hot_ to see him so worked up like this, and she wanted to get this thing _going_ already. So Tess reached between them and fumbled in the growing dark, trying to find the join of their bodies so that she could explore his body. She knew as soon as she had, because he gave off a metallic purring noise before buckling his hips towards her venturing hand. In the blind dark, she mentally mapped this unexplored territory of her lover's body.

The junction between his legs was warm, evidently a sign that he was preparing for interface. To her surprise, her fingers did find a form of 'protrusion' coming from a slightly raised, exposed piece of panelling which clearly was retractable. The 'penis' for lack of a better term, felt like a thick, silicon cable and when she ran her hands up along it, she felt his arms tremble around her. Curious, Tess continued her objective; wanting to know just what she was about to get herself into. It was roughly about 8 or 10 inches in length, and she found herself swallowing thickly. It would probably be an uncomfortable start, but she could deal with that…one of her previous lovers had been particularly _endowed_ to an almost uncomfortable level for her; but he'd not had much consideration when it had come to allowing her body to adjust.

Even in his darkest of states, she knew that _Optimus_ would never hurt her; he couldn't.

What interested her most was the head of the cable; it was a firm but malleable silicone substance that felt like it was shaped a little bit like the nose of an aeroplane. The entire protrusion was lightly ridged down the side, clearly for some kind of traction or grip while interfacing. He was bigger than she was _used_ to, but not impossible.

_Yeah_, she told herself reassuringly. She could do this.

As her exploring fingers curled around the length of thick cabling, above her Optimus gave a guttural snarl; apparently unwillingly thrusting forward once into her grip before grasping her shoulders bruisingly, burying his face into her shoulder and clamping his dentas down on the skin sharply.

"_Argh!_" she cried out, a pained gasp escaping her. In retaliation, she pinched the interface cable with her nails, dragging them agonisingly, almost _painfully_ from the base to the head.

Oh revenge was sweet.

"Let's take this somewhere more appropriate; alright?" she hissed, trying to reason with the illogical (_and quite frankly, horny_) Holoform as he continued to nip at her skin.

"Berth." He purred. However at first, Tessa didn't understand what it was that he was trying to say, the word itself confusing her.

"Birth? What do you mean _birth_?"

Another small thrust into her hand was his attempt to incoherently prove his point. "_Berth_!" he snarled. Trying to wrack her brains, Tess suddenly recalled hearing Ironhide and Ratchet use the term before. Usually they used it in reference to the gurney in the medical bay…why would he request a medical bay? Wait! Of _course_!

"You mean bed, right?" she breathed, planting a firm kiss to his lips and tracing her tongue along the metal, "You want the bed?"

The mech braced over her gave a pleased grumble, clearly glad that she had received his message clearly. The female's soft little hands wrapped around his interface equipment were wonderful; even if it was strange that they didn't particularly feel like _femme_ hands. His Spark had all but taken over now, it wanted her; it wanted the object of its affections to be wrapped around it and be as close as physically possible for Cybertronians. Running his glossa over the previous denta nip, his seamed nose nuzzled into her hair with a purr.

"My Tessa…" he growled.

She felt more relief than she'd thought she would at hearing him say that; because it meant that her Optimus was still in there, still recognized her as _her_. Releasing the thick cable, she managed to wriggle out from his grasp and took a few steps towards her bedroom; trying to ignore the fact that her top half was completely bare. She turned and looked back at him only to find that he was still on his knees on her sofa, watching her the way a wolf watches its hunt.

Predatory.

"I thought you wanted to take me to the berth, Optimus Prime…You don't want to interface with me anymore?" In a rather uncharacteristically teasing manner, she very briefly ran her hands over her chest before shaking her head in a mocking manner and shrugging as she turned to continue to down the hall towards her room, "Oh well…"

A loud, metallic thumping was heard; like running, and before she knew it, before she even knew _how_, she was slammed up against the wall at the end of the hallway. Her hands were pinned to the wall from behind, both her palms force flat against the wall as two large metal hands encased them. The tall, angular metal of Optimus' form was pressed against her back and he released one of her hands to wrap an arm around her waist; pulling her against him. She felt his metal lips nip at her shoulder before resting against her ear.

"My Tessa" He repeated with a snarl, "_My__ Tessa_!"

"Don't need-? _WHOA-!_"

In an instant, Optimus had gripped her by the thighs, spun her in a complete 180 and pinned her against the wall. Yeah, he _clearly_ had some sort of fetish for wall sex, because she _always_ seemed to end up this way…

But then again, they usually weren't romping around trying to figure out human-mech sexual relations.

Pinning her against the wall with his body, Tessa noticed that his demeanour was a fair sight more…aggressive this time; maybe she shouldn't have made that comment about not interfacing…Was _this_ the 'point of no return' Optimus had been trying to make before?

She was distracted from her thoughts by the Holoform grabbing tightly at her thighs and biting at her neck again.

He bit down _hard_, and this time he drew blood. She could feel the warm liquid seeping to the wound, but she didn't notice because it was fucking _hot_. Tightening her legs around him in an almost aggressive manner, she returned his fevered attitude with her own.

"You want to play rough, robot?" she snapped. Optimus replied with a Cybertronian garble in the midst of a possessive growl; and she took this as a yes, "_Fine!_"

Reaching up to his chest, she wrapped her hands around the miniature windshield that was attached to the hood, and _snapped_ it off. Upon registering the wonderfully painful sensation his optics whirred as they narrowed at her hands, watching the piece of himself dissipating into a flurry of electrical sparks. Slowly and dangerously, his gaze moved to meet her eyes as his metal lips peeled back in a snarl. Forcing her tighter between himself and the wall, she heard a sharp, ripping sound and felt the baggy pyjama pants she wore slacken as Optimus _tore_ off her _clothes_.

"H-Hey!" she protested, "Those were my favourite – _Oh!_"

A rumbling reverberated between them as he yanked the now shredded fabric away from her body, and Tess heard it hit the opposite wall with a muffled thump as his metal mouth pressed against hers possessively. His glossa invaded past her teeth, tracing the side of her tongue and relishing the textures of her mouth; his large fingers sliding up her thighs firmly towards the junction of her legs. Before she could make any motion or protest, his grip shifted bruisingly to her arms; holding her up as he released her mouth and dipped his head. Sharp dentas grazed along the skin of her stomach before snagging the fabric of her plain, cotton underwear before tearing them off violently with the metal teeth. Clearly smelling the air, he could taste the arousal in the atmosphere; and it was spurring…she smelt _different_ to a normal femme…but it didn't matter; because she was _his_.

All that matter was _claiming_ her, ensuring that no other Cybertronian would dare touch that which was his.

As he returned one of his hands to her thighs to hold her in place and the other braced itself against the wall, she brought her own to his chest, dragging her nails up over the metal with a screeching noise. Lithe fingers found the intricate gear bases of his finials, and she dug her fingers into them teasingly. Suddenly, a sharp scream escaped her as one of his metal fingers slipped between the crease of her legs and intruded her body.

In an instant she flailed, unable to control the rampant sensations that the _cold_ metal created inside the tight heat of her body. Clearly Optimus could feel the difference in temperature too, because the Holoform gave a purring growl of approval and nuzzled into her neck as he pushed the finger deeper; savouring the sensation. Inserting a second finger, Tess gave a gasp and dug her fingers between the plating on his abdomen; pulling and pinching at whatever sensitive wires she could reach in retaliation.

An almost feral snarl escaped Optimus as he dug his free hand into her thigh; bruising her skin in all the _right_ ways that worked, just as he crooked his other fingers inside of her body. With a growl of her own, she bent her face into his neck and _bit down_ on the thick wires at his neck; resulting in him giving a primal roar as his hand against the wall clenched into a fist.

Plaster and brick crumbled beneath his hand before he roughly extracted his fingers and pulled her tight against him and moving towards her bedroom; clearly through memory he knew where it was. But as the door swung open and it clicked shut behind them, any gentleness from their previous nights together was forgotten; this was _Cybertronian_ sex now.

Brutal and harsh, something that she'd never _seen_ from the Prime before.

As he threw her, literally _threw_ her, down on the mattress; he purred an appreciation at her lovely naked form. Cybertronian or not, primal mindset or not; he knew his mate when he saw her.

Oh _Primus_ he wanted inside her so badly. His spike ached at the promise of her body, and he found himself trembling anticipantly as he slunk towards her; greatly resembling some sort of predator. As he reached her, braced around her over the bed, his fingers reached up and fisted themselves into her silken tangles of long, copper-brown waves; tugging insistently for her head to lean backward. His teeth found her throat, femmes had always liked teeth marks their; and often he'd drawn Energon in the violent romps.

But just before his dentas imbedded themselves into the strangely non-femme material matter, something stopped him. The skin didn't hum beneath his mouth…it _beat_. A memory surged through him, a coherent thought in an otherwise lustfully violent instinct.

His Tessa was _delicate_.

Instead of sinking teeth at her throat, a kiss was planted instead. The lust-clouded Spark that was controlling his coherent thoughts decided on something else. Making her scream, making her want…making her _beg_.

Tracing his glossa down from her throat and southward over her collarbone toward her breasts, he traced it over each of them; relishing in the gasping moan that he got from doing so…but it was brief. The searingly warm, damp metal continued its trail downward, caressing the fine musculature of her stomach and he nuzzled his nose into her hips as his hands clasped at her legs.

Applying a small amount of force that was not needed, given her willingness, he pried her legs apart and pressed a bite to the inside of her thighs, growling appreciatively at the scent of sex in the air. His glossa licked at her thigh, trailing towards the small patch of hair nestled between her legs.

"Whoa, Chief…" she whispered incoherently as her hands slid across the blankets helplessly, "Y-you don't have to do tha – _AT_! Oh _my God_!" Her nails fisted into the sheets violently as that damp, devilish imitation of a tongue entered into her; causing something to pool in her stomach as it did.

The bipedal Holoform was relishing in the myriad of sensations that he was deriving from this experience. The taste of her centre was unusual; it didn't taste like femme's transfluid, or like oil or Energon. It was infinitely different; thicker, slicker…sweeter. It would be a lie to say it was unpleasant; in fact was far from it.

The scent of her body, the way she made that strange _mewling_ noise when he dragged his dentas across the small bundle of nerves at the front of the entrance just right. Experimentally, he pushed his glossa in deeper; trying to locate the source of his femme's incredible moisture; and he was rewarded by her fingers snaking down over the lip of his helm and pinching the sensitive finials that served as his ears.

"Shit…" she hissed through her teeth, "Oh my god…fucking _yes__!_"

Her nails dug deeply into the sensors at his neck, causing him to growl into her feminine parts with a heavy exhalation and his fingers to dig possessively into her thighs. They traced over the skin of her legs, pushing them a little further apart as he plunged his glossa deeper into her.

"_Oh_ Optimus! Fuck I – _nyaaAH_ – I _need_ you Optimus…Now – _please_!"

Surprisingly obediently, he did as she asked; but not before he rolled the tiny little protrusion between his teeth and making her thrash uncontrollably. But now that his 'prey' was laid out perfectly before him, the Cybertronian was unable to wait or hold back.

Placing himself between her already parted legs, he leaned over her and planted his mouth on her throat with slick, heavy kisses. His hands traced teasingly up her legs, up her thighs and onto her ass; lifting her hips firmly. The head of his interface cable was pressed against the warm entrance of her body and he lifted her pelvis possessively towards his; he bit down on the already punctured skin of her shoulder junction just as he pushed it past the soft folds, trying to use the bite to distract her.

A disbelieving, gasping squeak came from her as he sheathed himself inside her, the metal of his pelvic bone, abdomen and chest pressing coldly against her own; making her arch as she tried to make her body get used to the sensation.

Sweet holy Jesus, she'd never been _filled_ like this! Talk about buried to the hilt.

It took a little while longer than she was accustomed to, but eventually her body grew used to the intrusion; and she was surprised that with the 'primal' mood of the Holoform he had waited at all. Perhaps her Optimus had more control over his instincts than he thought he had.

All coherent thought was chased from her head, however, as he started to _move_ inside her.

Sweet merciful Primus she was so unbelievable soft, and tight, and _hot_; impossibly, searingly so.

"_Optimus_ – Oh my god-! F-Faster…"

Even Energon in its most molten form could not compete with this level of overbearingly pleasurable heat! Pit spawned fury, there would never be _enough_ of her to satiate him…Rhythm…he needed rhythm.

Grabbing her hips with a feral growl, the digits of his fingers dug into the flesh as he sealed her mouth in a kiss and began to thrust into her. Their previous, almost violent little romp had put them both so close to the edge already, but neither of them cared about how soon if would come. Tessa's legs wrapped as far around his large body as they would go, pulling him into her heat and squeezing her body to his in encouragement. Her fingers dug into the wires beneath his metal armour and oh _Primus_ it felt like magic. The moans that she made and that _clawing_ thing that she was doing to the undersides of his metal plating; the sensation was purely delicious!

Feeling the imminent overload fast approaching him, the bipedal Holoform growled and tightened one arm around Tessa's hips to pulled her deeper, and the other one he dug into her upper arm as he kissed her. He could sense her breathing growing erratic, and soon he understood why. With one last deep, pulsing thrust into her, the warm, _tight_ walls of her body seized around him; so _hotly_ that he was unable to hold back overload.

A guttural roar escaped him as he bared his teeth and rode out the climax inside her; the Energon lubricant filling his human lover as he did so. Whether intentionally or not, the tight heat milked his spike as her body continued to spasm for a minute longer. Finally she collapsed back onto the bed with heavy, panting breaths as the Holoform slowly pulled his interfacing cable out of her. Optimus could feel the unfortunate need to reset the Holoform; it was at its limit. He didn't want to leave her, even for a moment; but it was necessary.

Holding an arm over her body either side, he pressed his forehead to hers and murmured gently to her.

"I will be back, I need a minute…"  
>"No…problem, Chief…" she breathed heavily, catching her breath as she felt the Holoform's body dissipate from her room. Her chest heaved, her abdomen ached and sweat clung to her hair damply. "Holy…shit…"<p>

As she lay back on her bed, her eyes slid shut in bliss. The entire inside of her body felt tingly…like there were electrical synapses being _lit_ inside her. Her skin tickled gently and her toes curled at the leftover sensations from the orgasm. She was guaranteed to be…_sore_ in the morning…but it was so worth it. She had to have dozed off, because the next thing she knew, the human Holoform of Optimus was murmuring her name.

Optimus had indeed returned to find her sleeping, and sat gently on the side of her bed to watch her. He'd only really just regained full coherency from the overload; he'd been so lost to instinct that he was worried about whether he had hurt her or not.

With his ability to see in the darkness, surveying her naked form was not a challenge, and the moment he saw bruises…_bruises_ forming on _his Tessa's_ body, he made a decision.

"Tessa…" he murmured gently, stroking the human Holoform's hand along her jaw tenderly just to feel her soft skin against his. Her eyes fluttered open as she took him in.

"Optimus…" she breathed, sounding so loving and unsuspecting, despite him having _harmed_ her. Oh how he _hated_ himself right now.

"Tessa…" he repeated, leaning over to plant a kiss on her mouth gently, "…we are not doing that again."

Seemingly unable to do much more than widen her eyes due to exhaustion, the little mechanic turned her head and ran a hand lovingly through his hair. "How come…?"

Cringing at the thought that he had harmed her, he pressed a hand to one of the forming bruises on her thighs and to the seeping bite mark – o_h dear sweet Primus, a __BITE MARK?_ –on her shoulder, "Because I…I've hurt you…Tessa I'm…so _sorry_…"

Suddenly worried, she noticed the Holoform's hands trembling and she moved to take them in her own, "Hey…hey – Chief you're _shaking_! Look at me. Hey – look at me!" she cupped his chin in her fingers and pressed her forehead against his; lowering her voice to a gentle whisper, "I _wanted_ this, Optimus. Don't _think_ anything of this; that was amazing. Seriously."

He cupped her face on both hands and kissed her fiercely, deeply; lovingly before he shook his head and murmured to her.

"Even so…I will not take another chance like that; we _are not_ doing that again, Tessa. I _won't_."

The little mechanic smiled and grabbed the Holoform's shirt, pulling him to lay down beside her as she traced his lips with her thumb; her eyes burning into his. "I understand. Don't worry Optimus, I just wanted to _try_ it once. I'm not going to do anything that makes you uncomfortable; I _love_ you."

Sliding his arms around her protectively and pulling her against him, he tucked her head underneath his chin and gave a heavy sigh; his chest reverberating through the both of them like sinfully sweet thunder. "And I love you. I will never allow myself to hurt you like that again, Tessa; I swear…"

A giggle bubbled up from her tiredly as she pressed a languid, completely relaxed kiss on his neck. "Silly old robot…" she whispered.

He buried his face lovingly into her hair, relieved more than words could express, that she was safe; from his instincts. "I may be a 'silly old robot' Tessa, but I'm _your_ silly old robot." His hands tightened around her as he pulled her in to a protective embrace, ready to try and swallow her up from ever being harmed for as long as she lived. To his surprise, he heard her rumble a dark, almost growling response as _her_ fingers tightened protectively against him.

"Yeah. _Mine_…"


End file.
